The Farnsworth Test is a test to diagnose color blindness that allows the ophthalmologist to measure the visual capacity that a person has to distinguish shades of colors.
Through this test, color alterations can be classified, or dyschromatopsias, to know exactly the type of color blindness that a patient presents.
Next, in Área Oftalmológica Avanzada We explain what the Farnsworth test is and what it consists of. Keep reading!
What is the Farnsworth test?
The Farnsworth test was created in 1943 by the Commander of the United States Navy, Dean Farnsworth, and is one of the most used tests to measure the visual capacity that a person has when it comes to distinguish colors.
This test is made up of 100 capsules of different colors and each shade is differentiated from another by a slight gradual variation, so that there is an appreciable but not obvious difference.
Also, the test contains four trays with 25 capsules, and each tray represents an interval of the color spectrum.
The objective of the test is for the patient to observe the four trays with their combined capsules and order them in one time. maximum of 8 minutes, that is, 2 minutes per tray.
What pathologies does it detect?
The Farnsworth test allows diagnose dyschromatopsia, which are visual limitations to correctly distinguish colors and differentiate some tones from others.
The best known dyschromatopsia is colorblindness, a congenital and genetic condition that originates from the absence of one or more cones of the retina.
Cones are color-sensitive photoreceptor cells that are grouped into three types: one group of cones detects color red, another group the green and another the azul. The absence of one or more types of cones it is what produces color blindness.
People with problems solving the Farnsworth test have difficulty or inability to distinguish the color red (protanopia) and green (deuteranopia).
Although also common but less common, some patients also have problems distinguishing the color blue and yellow.
How is this test performed?
To perform the Farnsworth test, the patient must be 50 centimeters away from the tray with the colored capsules. The ideal is to do the test in sunlight and place the tray on a black background.
Each tray contains 25 colored capsules. The first and last capsule are the pilot colors for that tray.
And what should the patient do? Starting with the first color, you must order the capsules of the medium also taking into account the last color. The test is carried out in a time maximum of 8 minutes.
Once the test has been performed, the doctor will turn the capsules over to write down the number of each one of them and obtain the numerical series in which the patient has ordered the ranges of colors.
If the order of the capsules is correct, the result throws a circle of points in the center of the diagram. If it is not, there will be scattered points on the diagram, located in the color that the patient cannot correctly distinguish.
Do you have any symptoms of color blindness? In Área Oftalmológica Avanzada We have the best qualified team to carry out the Farnsworth Test. Call us!
